Author:

Keywords:

Animals, Dose-Response Relationship, Drug, Gene Expression, Humans, Insect Proteins, Membrane Potentials, Microinjections, Molecular Sequence Data, Neurotoxins, Oocytes, Patch-Clamp Techniques, RNA, Complementary, Research Support, Non-U.S. Gov't, Scorpion Venoms, Scorpions, Sequence Homology, Amino Acid, Sodium Channel Blockers, Sodium Channels, Xenopus, Science & Technology, Life Sciences & Biomedicine, Biochemistry & Molecular Biology, Biophysics, Cell Biology, voltage-gated sodium channel, inactivation, scorpion, alpha-toxin, Buthus, Buthidae, GATED SODIUM-CHANNELS, SCORPION TOXINS, MOLECULAR-MECHANISMS, NEUROTOXIN, PURIFICATION, SELECTIVITY, EXPRESSION, SEQUENCES, MUSCLE, CLUE, 0304 Medicinal and Biomolecular Chemistry, 0601 Biochemistry and Cell Biology, 0603 Evolutionary Biology, 3101 Biochemistry and cell biology

Abstract:

The present study investigates the electrophysiological actions of BmK M1, an alpha-like toxin purified from the venom of the scorpion Buthus martensi Karsch, on voltage-gated Na+ channels. Using the voltage clamp technique, we assessed the BmK M1 activity on the cardiac Na+ channel (hH1) functionally expressed in Xenopus oocytes. The main actions of the toxin are a concentration-dependent slowing of the inactivation process and a hyperpolarizing shift of the steady-state inactivation. This work is the first electrophysiological characterization of BmK M1 on a cloned Na+ channel, demonstrating that this toxin belongs to the class of scorpion alpha-toxins. Our results also show that BmK M1 can be considered as a cardiotoxin.